Vacuum apparatus



Sept. 9, 1930. KRAMER 1,775,531

VACUUI APPARATUS Filed June 24, 1924 Im/ent or Christian Kr-rner,

His Attorney.

continuously during 1 metal receptacles. and relatively Patented Sept.9, 1930 UNITED'STATES PATE T oFF1ca- 01:31am or umrow, eminent, ASSIGNOB'ro cmmr. unarme 00l- PANY, A CORPORATION 01 NEW YORK VAO'UUM APPARATUSApplication fled Jane M, 1924, Serial Io. 782,188, and in Germany July19, 1988.

The present invention relates to the maintenance of a desired pressurein a device, such as a mercury arc rectifier, for example, in whichsmall amounts of gas are evolved operation.

A mercury 'arc recti er preferably should be operated with a gaspressure less than about 0.005 to 0.01 m. m. of mercury. Large powerrectifiers which usually reTiire large arge elec trode masses are apt togive 0 gas gradually during operation so that the vacuum becomesprogressively poorer. When the gas pressure exceeds a permissible valuethe vacuum pump again must be put into operation in order to reduce thegas pressure to the re-' quired value. As there are no reliableautomatically operating devices which are responsive to such small gaspressures, the state of the vacuum of a power rectifier must becontinuously supervised by an attendant. Obviously this necessity forcontinuous supervision of the rectifier is disadvantageous and contrastsunfavorably with the operation of other electrical devices, such astransformers, in the station in which the rectifier is employed.

It is'the object of my present invention to reduce the supervisionrequired for the operation of large rectifiers, that is, to provide anarrangement whereby automatic serviceless operation for relatively longperiods of time is secured.

In accordance with my invention, the device in which a good vacuum is tobe maintained is continuously exhausted by an exhaust means having nomoving mechanism, and hence re uiring no supervision, and the gasremoved y this means is received by an exhausted space of relativelylarge capacity, thereby permitting operation for relative long periodsbefore the pressure in the large capacity space becomes too high topermit of further operation.

The accompanying drawing illustrates somewhat diagrammatically aninstallation for carrying out my invention. In the drawing a mercury arcrectifier 1 is connected by a conduit 2 to the exhaust tube 3 of a vaporjet pump which in turn is connected to a conduit 4, 4' whereby theexhausted gases are conducted to a container 5hav1ng a materially largercubical capacity than the mar-- is inductively interlinked with themercury,

constituting the secondary, by a magnetic core 9 as indicated.Communicating with the receptacle 6 are two ducts 10 and 11 whichcommunicate at the o posite ends with the exhaust tube 3. In 51c drawingwhich is merely diagrammatic these ducts terminate at the lower inclinedsurface of the tube 3 but, of course, they may be of any otheradvantageous construction. Surrounding the exhaust tube 3 is a suitablecooling means, such as the water jacket 12, which is provided with aninlet tube 13 and an outlet tube 14 as indicated. When the mercury isheated and vapor rises through the ducts 10 and 11, gas is drawn fromthe device 1 through the conduit 2 and accumulated in the conduit 4 inaccordance with the now well understood method of operation of vapor orcondensation pumps. Mercury vapor is condensed during this operation andthe globules of condensed mercury are returned to the receptacle 6 by aconduit 15. The duct 10 will convey gas taken from the conduit 2 in arelatively good vacuum and deliver it to the exhaust tube neartheterminal of the duct 11 at a pressure of about 0.2 m. m. where it isfurtherraised to a pressure. of about 30 to 50 m. m.

Included in the conduit 4, 4 is a valve constituted by a receptacle 17containing a quantity of mercury 18 into which the end of the tube 4dips. When the gaseous pressure in the conduit 4 has become high enoughto overcome the pressure of the mercury surrounding the lower end ofthis conduit, the mercury will be displaced and some of the 3 beendiagrammatically combination of a receptacle in w gas will flow into thelarge vacuum container 5."

The mercury vs rlzlipor pump requires no supervision and operatecontinuousl to exhaust small amounts of gas given oil by the rectifier 1during 0 eration; These gases are accumulated at a igher pressure in theconduit 4 as already described and fed intermittently into the tank 5until the pressure in the tank becomes so high that no more gas canescape from the conduit 4. In other words the system will operate untilthe pressure in the conduit 4 becomes high enough to be in equilibriumwith the pressure which is delivered by the vapor pump, without beingrelieved by escape into the tank 5. It then becomes necessary to againexhaust'the tank -5, for example by starting into operation a 'vacuumpump 19 and opening a valve 20 in the conduit 21 which connectsthe pump'19 with the tank 5. When the tank has been --re-evacuated, the valve 20is closed and the pump 19 is stopped. In the drawing the vvalve 20 hasbeen shown as being operated .electromagnetically but, of course, insome cases manual operation may be preferred,

the operating magnet then being omitted.

An automatic contact manometer 22 has indicated, whereby the exhaust pummay be automatically put into operation w en the gas pressure in thetank 5 has risen to a predetermined value.

The mercury column in the manometer then 'willcomplete an electricsupply circuit 23,

thereby opening the valve 20 by a magnet 24 and starting theelectrically driven pump 19. Suitable relay devices, of course, may beused as well understood in the art.

As the size of the tank 5 can be made relatively large as compared withthe size of the rectifier 1, (as indlcated by its being shown as broken}the system will operate .for a relatively ong er1od without supervision.

' When the tu e 4 is made of barometric height, that is, at least 760 m.m. then in case the tank 5 is opened, or for any reason loses itsvacuum, no air still can reach the rectifier as the mercury cannot risehigher than 760 m. m. in the tube 4.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is 1. A vacuum apparatus com rising the ich a high vacuum is tobe maintained and in which small amounts of gas are apt to be evolved,means for continuously exhausting gas from said rece tacle, a containerof larger capacity than sai receptacle connected to receive gas fromsaid exhaust means and a valve for preventing the back flow of gas fromsaid container.

2. The combination of a mercury are device, means for continuouslyexhausting gas therefrom, a container of larger capacity than saidreceptacle connected to receive gas the flow of gas to said tank butfrom said exhaust means and meansfor pre venting the back flow 0t gasfrom said container to said arc device.

3. The combination of a mercury vapor rectifier, a condensation pu npconnected thereto, a tank having a larger volume content than saidrectifier and connected to receive gas from said condensation pump, amechanical pump for evacuating said tank and a mercury seal locatedbetween said condensation ump and said tank permitting preventing flowof gas in a reverse direction.

4. The combination of a vapor condensation pum a mechanical pump, acontainer connecte between said pump, a mercury seal arranged to permitthe flow of gas only in one direction between said condensation pump andsaid container, and means arranged to open the connection between saidcontainer CHRISTIAN KRAMER.

